System for supplying gas to at least one gas-consuming appliance equipping a ship

Abstract

A system for supplying gas to at least one gas-consuming appliance equipping a ship, the supply system includes at least one gas supply line for supplying gas to the at least one gas consuming appliance, the gas supply line being configured to be traversed by gas taken in the liquid state from a tank and subjected to a pressure lower than a pressure of the gas in a headspace of the tank, a first compression member configured to compress the gas from the gas supply line for supplying gas to the at least one gas-consuming appliance, a second compression member, characterized in that the first compression member and the second compression member alternately compress gas in the gaseous state from the gas supply line and gas taken in the gaseous state from the headspace of the tank.

The invention claimed is: 
     
         1 . A gas supply system for supplying gas to at least one gas-consuming appliance equipping a ship, the supply system comprising:
 one gas supply line for supplying gas to the at least one gas-consuming appliance, said gas supply line being configured to be passed through by gas taken in the liquid state from a tank and subjected to a pressure lower than a pressure of the gas in a headspace of the tank;   one first compression member configured to compress the gas from the gas supply line for supplying gas to the at least one gas-consuming appliance; and   one second compression member,   wherein the first compression member and the second compression member alternately compress the gas in the gaseous state from the gas supply line and the gas taken in the gaseous state from the headspace of the tank,   wherein at least one pipeline is arranged between the headspace of the tank and an intermediate inlet of the first compression member, at least one control member being arranged on the at least one pipeline, and   wherein the intermediate inlet of the first compression member is arranged so that the gas taken in the gaseous state from the headspace of the tank mixes with an evaporated gas at a point of the first compression member at which this evaporated gas is already compressed to the pressure of the gas present in the headspace of the tank.   
     
     
         2 . The gas supply system as claimed in  claim 1 , comprising at least one heat exchanger configured to implement a heat exchange between the gas which flows in the supply line and gas taken in the liquid state from the tank. 
     
     
         3 . The gas supply system as claimed in  claim 2 , wherein the heat exchanger is equipped with at least one first pass configured to be supplied with the gas taken in the liquid state from the tank of the ship and at least one second pass configured to be supplied with the gas subjected to a pressure lower than the pressure of the gas in the headspace of the tank. 
     
     
         4 . The gas supply system as claimed in  claim 3 , comprising at least one first pump configured to supply the first pass of the heat exchanger, one second pump configured to supply the second pass of the heat exchanger, at least one expansion means being arranged on the supply line, between the second pump and the second pass of the heat exchanger. 
     
     
         5 . The gas supply system as claimed in  claim 1 , wherein the first compression member and the second compression member suck in the gas taken from the headspace of the tank. 
     
     
         6 . The gas supply system as claimed in  claim 1 , comprising as a compression member only the first compression member and the second compression member. 
     
     
         7 . The gas supply system as claimed in  claim 1 , comprising at least one reliquefaction system for gas compressed by the first compression member and/or by the second compression member. 
     
     
         8 . The gas supply system as claimed in  claim 7 , in which the reliquefaction system comprises at least one first heat exchanger equipped with at least one first pass configured to be passed through by gas compressed by the first compression member and/or by the second compression member and with at least one second pass configured to be passed through by gas taken in the gaseous state from the headspace of the tank. 
     
     
         9 . The gas supply system as claimed in  claim 8 , wherein the reliquefaction system comprises at least one second heat exchanger configured to implement a heat exchange between compressed gas leaving the first pass of the first heat exchanger and gas taken in the liquid state from the tank. 
     
     
         10 . The gas supply system as claimed in  claim 1 , wherein the first compression member is configured to be supplied with gas having a pressure between 0.35 and 0.7 bar and to compress this gas to a pressure between 2 bar and 13 bar, and wherein the second compression member is configured to be supplied with gas having a pressure equivalent to 1 bar and to compress it to a pressure between 5 bar and 20 bar. 
     
     
         11 . The gas supply system as claimed in  claim 1 , wherein the first compression member and the second compression member are connected in series with each other. 
     
     
         12 . The gas supply system as claimed in  claim 11 , wherein at least one first conduit is arranged between an outlet of the first compression member and an inlet of the second compression member, at least one pressure control means being arranged on this at least one first conduit. 
     
     
         13 . The gas supply system as claimed in  claim 12 , wherein at least one second conduit is arranged between an outlet of the second pass of the first heat exchanger and an inlet of the first compression member, at least one first flow control means being arranged on this at least one second conduit. 
     
     
         14 . The gas supply system as claimed in  claim 11 , wherein the first compression member is configured to be supplied with gas having a pressure of between 0.35 bar and 0.7 bar and to compress it to a pressure of between 2 bar and 6 bar, and wherein the second compression member is configured to be supplied with gas having a pressure equivalent, or substantially equivalent, to 1 bar and to compress it to a pressure of between 5 bar and 20 bar. 
     
     
         15 . The ship for transporting liquefied gas, comprising the at least one tank of a liquefied gas cargo, the at least one evaporated-gas-consuming appliance and the at least one system for supplying gas to the at least one gas-consuming appliance as claimed in  claim 1 . 
     
     
         16 . The ship as claimed in  claim 15 , comprising at least one first gas-consuming appliance configured to be supplied with gas compressed at a first pressure, and at least one second gas-consuming appliance configured to be supplied with gas compressed at a second pressure, the first gas-consuming appliance and the second gas-consuming appliance both being configured to be supplied by the at least one supply system, and the first supply pressure of the first gas-consuming appliance being higher than the second supply pressure of the second gas-consuming appliance. 
     
     
         17 . A gas supply system for loading or unloading a gas in a liquid state which combines at least one onshore means and at least one ship for transporting gas in the liquid state as claimed in  claim 16 . 
     
     
         18 . A method for loading or unloading the gas in a liquid state from the ship for transporting gas as claimed in  claim 15 .